Liquid crystal display device is widely used for its perfect characteristics. Its working principle is as follows. Liquid crystal molecules are placed between two substrates, and different electrical fields are applied at different locations of the substrates so that the liquid crystal molecules are rotated differently so as to control light from backlight to deflect in different manners, which leads to different luminance of the emitted light, and thus image display is achieved.
Liquid crystal molecule as a display material is closely related to display quality of the liquid crystal display device. Blue phase (BP) is a phase state of liquid crystal having special properties, within a narrow temperature range (about 0.5 to 2 centigrade) between cholesteric phase and isotropic phase, and the phase state is stable. Because liquid crystal in this phase state usually appears blue, this phase state of liquid crystal is called blue phase. Blue-phase liquid crystal, as a promising liquid crystal display material, has the following advantages: (1) quick response speed (less than 1 ms), which makes field sequential color display possible; (2) capable of implementing display by directly using electric-field-induced birefringence principle (i.e., Kerr effect) without using a alignment layer; (3) good isotropy of liquid crystal when powered off, no light leakage in dark state, and good visual angle.
In a display device of the prior art, blue-phase liquid crystal is usually driven by transverse electric field. In this case, common electrodes and pixel electrodes are typically arranged in two manners. In the first arrangement manner, as shown in FIG. 1, common electrodes 3 and pixel electrodes 4 are only arranged on a lower substrate 101. In the second arrangement manner, as shown in FIG. 2, in a case that the common electrodes 3 and the pixel electrodes 4 are arranged on the lower substrate 101, the common electrodes 3 and the pixel electrodes 4 are also arranged on an upper substrate 102, and positions of the same type of electrodes on the two substrates are opposite to each other. In the above two manners for arranging the electrodes, the common electrodes 3 and the pixel electrodes 4 each are of bar shape, their numbers are more than one respectively, and they are arranged alternately and in parallel with each other. Electric field intensity of the transverse electric field for driving liquid crystal generated by the two types of electrodes as arranged in either of the above two manners is relatively weak, thus only liquid crystal molecules which are located near the pixel electrodes 4 and the common electrodes 3 in a same plane are driven to stretch to exhibit anisotropy, while it is difficult to obtain a relative uniform horizontal electric field in a large thickness range of liquid crystal cell. Thus, higher driving voltage is necessary.
In the prior art, there is also disclosed a display device in which blue-phase liquid crystal is driven by using wall-like electrodes to generate transverse electric field. As shown in FIGS. 3 and 4, wall-like electrodes are arranged on the upper substrate 102 and the lower substrate 101, comprises the common electrodes 3 and the pixel electrodes 4, and has surfaces with wrinkles. Height of a wall-like electrode is larger than that of a normal electrode, which can achieve a relative uniform horizontal electric field in the large range of thickness of liquid crystal cell. In addition, the wrinkles can further enhance the electric field intensity, which decreases required driving voltage for blue-phase liquid crystal.
The inventor has found that at least following problems exist in the prior art: for the current driving manners for blue-phase liquid crystal, on one hand, higher driving voltage is needed when using a manner of normal transverse electric field; on the other hand, when using the wall-like electrodes to drive, since the wall-like electrodes have complex shapes, it is difficult to manufacture, and feasibility of process is poor.